Movement for healthy life has recently positively been taken in Japan aiming at improvement of lifestyle, reduction of risk factors, or reduction of diseases, and awareness for healthy life has been raised globally.
Particularly, with respect to circulatory diseases, it is assumed that for example, when the blood pressure of people of Japan is lowered in the degree of 2 mmHg in average, fatalities due to cerebral stroke will be reduced about 10,000 persons, and lowering of activities of daily living (ADL) of 3,500 persons can be prevented.
From the viewpoint of the above circumstance, various kinds of foods have been developed, those containing a food protein-origin peptide which has hypotensive activity.
For example, it has been reported that a peptide or a peptide mixture obtained by lysing cow's milk-origin casein with trypsin or pepsin include one or more peptides having a sequence of (a) Phe-Phe-Val-Ala-Pro-Phe-Pro-Glu-Val-Phe-Gly-Lys (Seq. ID No. 1) (hereinafter, occasionally referred to as “C12”), (b) Ala-Val-Pro-Tyr-Pro-Gln-Arg (Seq. ID No. 2) (hereinafter, occasionally referred to as “Cβ7”), and (c) Thr-Thr-Met-Pro-Leu-Trp (Seq. ID No. 3) (hereinafter, occasionally referred to as “C6”), or an acid addition salt thereof, which have an inhibitory activity to angiotensin converting enzyme (hereinafter, abbreviated as “ACE”) (cf. JP-B -60-23085, JP-B-61-51562, and JP-B-61-51564); that a crude composition comprising mainly the above-mentioned peptide or peptide mixture (such a crude composition is also included in the peptide of the present invention) has ACE inhibitory activity likewise (cf. JP-B-5-21092). It has been expected that the peptide or peptide mixture will be useful as a material not only for the treatment of hypertension but also for the prevention of hypertension (cf. JP-B-4-58947, JP-A-64-9938 and JP-A-1-187067). Moreover, it has been known that a pepsin-lytic product of cow's milk casein has sedative activity (JP-B-5-81220); that a trypsin-lytic product of cow's milk-origin casein has hyperlipidemia inhibitory activity (cf. JP-A-6-211690) or has an activity of prevention of cerebral stroke (cf. U.S. Pat. No. 5,703,212).
It is also known that the foods-origin peptide or peptide mixture as mentioned above have usually strong bitter taste and/or astringent taste.
It has been tried to reduce or modify such bitter taste and/or astringent taste of the foods-origin peptide or peptide mixture by using various kinds of additives. For example, JP-A-9-249694 discloses an aqueous solution suitable for oral administration which comprises (a) a peptide or peptide mixture having bitter taste and/or astringent taste, (b) a sugar alcohol, (c) an acidic flavor, and (d) a plum type flavor.
On the other hand, it has been know that as to the electrolyte excretion promoter to be used in the present invention, chitosan has an activity of binding to chlorine contained in foods to excrete it out of the body, and alginic acid or a salt thereof has an activity of binding to sodium contained in foods to excrete it out of the body, and hence, these substances are used as a material for healthy foods for the purpose of low-salt diet.
Research and development of chitosan (β-1,4′-poly-D-glucosamine) have been done in various fields and is has been used in various kinds of products. Chitosan is produced by partially or completely de-acetylating a polysaccharide chitin (β-1,4′-poly-N-acetyl-D -glucosamine) which composes shell of shellfish or cuttlebone, and various products having various molecular weights are commercially available. Alginic acid is a natural polysaccharide which is contained particularly in brown color weeds such as sea tangle and wakame seaweed.
In has been known that chitosan has also an hypotensive activity. For example, JP-A-6-56674 discloses a food additive comprising chitosan as an active ingredient which is useful for promoting excretion of chlorine in foods and a food additive comprising chitosan as an active ingredient which is useful for hypotension. However, the hypotensive activity of the product is merely effective for inhibiting rise of blood pressure due to increase of chlorine in serum after taking high salt diet, but it is not expected to reduce the blood pressure after taking a normal food in such a degree as in the case of taking of high salt diet. (cf. Chitin-to-Chitosan Kiso-to-Yakuri (Basis and Pharmacology of Chitin and Chitosan), 3rd Edition, pp. 28-35, edited by Takumichi OKUDA, Yakkyoku Shinbunsha, 1997).
Moreover, alginic acid has also been known as one of the components of sea tangle, of which hypotensive activity has been known from a long time ago. That is, it is considered that the hypotensive activity of sea tangle will be exhibited by binding alginic acid to sodium contained in the ingested foods and then excreting it out of the body. Thus, the hypotensive activity will be exhibited owing to desalt effect and thereby a salt-sensitive hypertension will secondarily be prevented.
Any of the patent publications and literatures as mentioned above do never disclose a composition comprising a peptide or a peptide mixture which is obtained by lysing a food-origin protein with a protease and has an inhibitory activity to ACE and an electrolyte excretion promoter.